Let's break down the question step by step: --- ## **Question Analysis** **What is the major product of the following reaction?** You have: - A diene (on the left) — 1,3-butadiene structure. - A dienophile (on the right) — an alkene with two ester groups (dimethyl maleate). - The reaction is heated (Δ). --- ## **Reaction Type** This is a classic **Diels-Alder reaction**. ### **Diels-Alder Reaction:** - A [4+2] cycloaddition between a conjugated diene and a dienophile. - Forms a six-membered ring. - Stereochemistry is preserved—cis dienophile leads to cis products. --- ## **How to Predict the Product:** 1. **Align the Diene and Dienophile:** - The diene (left) and the dienophile (right) react to form a cyclohexene ring. - The two CO₂Me groups on the dienophile stay on the same side (because they started cis). 2. **Draw the Product:** - The product is a substituted cyclohexene. - The CO₂Me groups will be *cis* to each other in the ring. --- ## **Analyzing the Choices** Let's look at the options: - **Option 1:** Shows both CO₂Me on adjacent carbons and both are on the same side (cis). - **Option 2:** "No reaction" (incorrect, as Diels-Alder always proceeds with suitable substrates). - **Option 3:** Shows CO₂Me on adjacent carbons, but one is wedged and one is dashed (trans). - **Option 4:** Shows CO₂Me groups separated by a CH₂ group (not correct for Diels-Alder of these reactants). --- ## **Correct Answer** **The correct product must have the two CO₂Me groups cis to each other on the cyclohexene ring.** **So, the correct answer is the first option.** --- ### **Summary Table** | Option | Description | Correct? | Reason | |--------|--------------------------------------------|----------|----------------------------------| | 1 | Both CO₂Me groups cis (same side) | Yes | Matches Diels-Alder stereochem | | 2 | No reaction | No | Reaction occurs | | 3 | CO₂Me groups trans (opposite sides) | No | Not matching starting stereochem | | 4 | CO₂Me groups not adjacent | No | Not matching Diels-Alder product | --- ## **Key Points** - Diels-Alder is a [4+2] cycloaddition. - Stereochemistry of the dienophile is preserved. - For **cis** substituents on the dienophile, you get **cis** substituents on the product. **Let me know if you want to see the step-by-step drawing!**